engleski

Genetic heterogeneity of L-Zagreb mumps virus vaccine strain

Mumps virus belongs to RNA viruses. Due to the imprecision of RNA polymerase it contains a spectrum of viral genomes that differ in one or few nucleotides (quasispecies population). Consensus sequences of the L Zagreb master seed and a final vaccine were shown to be identical. Herein, we confirm the quasispecies nature of L-Zagreb using a combination of various methods (cloning, sequencing, plaque formation and PCR-RFLP). We isolated viral clones identical to consensus sequence (named ″ variant A″ ) and those that were different from consensus sequence in tree nucleotide positions (named ″ variant B″ ). In all analyzed samples (master seed, working seed and final vaccines lots) we detected both variants but within different ratio. The rate of variant B increased with the increasing number of subcultivation in the primary culture of chicken embryo fibroblast while the Vero and SH-SY5Y cells negatively selected variant B. Our data display influence of the cell culture and the number of virus passage on the heterogeneity of viral sample. Also, they notify the importance of consistent production of live attenuated vaccine strains.

mumps; vaccine; quasispecies; heterogeneity

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